JPH09292752A - Multicolor image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an excess of load on a drive part in the case of image formation in two or more colors and to stabilize an image in one color, in a multicolor image forming device. SOLUTION: This device obtains a multicolor image by superimposing and transferring visible images of different colors, formed on a photoreceptor drum 9 in order, onto an intermediate transfer belt 11 one on top of the other, and by transferring the superimposed images onto transfer paper all at once. It is equipped with a drive mechanism for driving the intermediate transfer belt 11 in the direction of transfer and in its opposite direction, a flywheel 43 which rotates accompanying the drive of the intermediate transfer belt 11, a clutch 44 for connecting/separating the flywheel 43 to/from the intermediate transfer belt 11, and belt contact/separation mechanisms 22, 24, and 25 for bringing the intermediate transfer belt 11 into contact with the photoreceptor 9 and separating it therefrom. In the case of copying in two or more colors the flywheel 43 is brought into contact with the intermediate transfer belt, and in the case of copying in one color it is separated therefrom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming apparatus using an intermediate transfer belt, and more particularly to a multicolor image forming apparatus provided with a flywheel that rotates with the driving of the intermediate transfer belt.

[0002]

2. Description of the Related Art A multicolor image forming apparatus such as a color copying machine
Multicolor images are obtained by sequentially transferring visible images of different colors sequentially formed on the photoconductor onto the intermediate transfer belt in a superimposed manner and transferring the superposed images onto a transfer sheet at once. In such an image forming apparatus, a flywheel is attached to a rotating unit such as a photoconductor to obtain stable rotation of the rotating unit and obtain a good image without color misregistration. .

In an image forming apparatus equipped with such a flywheel, when it becomes necessary to stop the photoconductor due to a paper jam or the like, the photoconductor does not immediately stop due to the inertial force of the flywheel. There was a problem of worsening. To solve such a problem, JP-A-4-2885
In No. 59, when it is necessary to stop the photoconductor drum due to a paper jam or the like, the constraint between the photoconductor drum drive system and the flywheel is released, thereby separating the inertial force of the flywheel from the photoconductor drum, The sudden stop is possible.

[0004]

However, in a multicolor image forming apparatus using an intermediate transfer belt, when copying two or more colors, after transferring a visible image of each color from the photoreceptor to the intermediate transfer belt. , The image is separated from the photoconductor, is fed backward, and moves to the initial position to transfer the next visible image on the previous visible image, and in the case of copying one color, the intermediate transfer belt It does not reverse. In such a multi-color image forming apparatus involving forward / reverse rotation of the intermediate transfer belt, there is a problem that the inertial force of the flywheel hinders smooth operation of at least one of the two-color or one-color process. there were.

Therefore, in the present invention, when the image of two or more colors is formed, the flywheel is released, and when the image of only one color is formed, the flywheel is connected to form an image of two or more colors. The purpose is to prevent an excessive load from being applied to the drive unit when forming the image and to stabilize the image for one color.

[0006]

A multicolor image forming apparatus according to the present invention is a multicolor image forming apparatus according to claim 1, wherein visible images of different colors sequentially formed on a photosensitive member are sequentially superposed on an intermediate transfer belt. In a multicolor image forming apparatus for obtaining a multicolor image by collectively transferring the superposed images onto a transfer paper, and a driving mechanism for driving the intermediate transfer belt in a transfer direction and in a direction opposite to the transfer direction. A flywheel that rotates as the intermediate transfer belt is driven, a clutch that connects or disconnects the flywheel to or from the intermediate transfer belt, and a belt contact / separation mechanism that contacts or separates the intermediate transfer belt from or on the photoreceptor. And the flywheel is connected to the intermediate transfer belt when copying two or more colors, and the flywheel is connected to the intermediate transfer belt when one color is copied. Characterized in that to separate against the belt.

According to the second aspect of the present invention, the intermediate transfer belt is separated from the photoconductor after transferring a visible image of each color from the photoconductor to the intermediate transfer belt when copying two or more colors. It is characterized in that the next visible image is transferred and superposed on the previous visible image by being moved back to the initial position.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a multicolor image forming apparatus of the present invention. A color image reading device (hereinafter referred to as a color scanner) 1 is driven by a stepping motor (not shown), and forms an image of an original on a color sensor 5 via an illumination lamp 2, a mirror group 3, and a lens 4. And the color image information of the original is, for example, blue (B),
Each color separation light of green (G) and red (R) is read and converted into an electrical signal.

Based on the B, G, and R color-separated image signal intensity levels obtained by the color scanner 1, color conversion processing is performed by an image processing unit (not shown) to obtain black (Bk), cyan (C), Color image data of magenta (M) and yellow (Y) is obtained. This image signal is converted into an optical signal, and optical writing corresponding to the original image is performed by a laser via the polygon mirror 6, the f / θ lens 7 and the reflection mirror 8 to electrostatically charge the photosensitive drum 9 of the drum unit. A latent image is formed. This latent image is developed by the developing device 10 and transferred to the intermediate transfer belt 11.

The latent image is transferred to the intermediate transfer belt 11 for each of the colors Bk, C, M, and Y, and as a result, a four-color superimposed toner image is formed on the intermediate transfer belt 11. The four-color superimposed toner image is transferred onto the transfer paper sent by the carrying roller 12 by the voltage applied to the paper transfer roller 13. The transfer paper after the image transfer is carried to the fixing device 15 by the paper carrying unit 14, and the toner image is fused and fixed.

In the above embodiment, the multicolor image forming apparatus employs a switchback system to prevent the transfer position shift of each Bk, C, M and Y image on the intermediate transfer belt 11. In the switchback method, the intermediate transfer belt 11 is brought into contact with the photosensitive drum 9 and then rotated in the forward direction (arrow F in the figure) to transfer the first color image on the photosensitive drum 9 onto the intermediate transfer belt 11. Transfer to. Next, the intermediate transfer belt 11 is separated from the photoconductor drum 9, and the intermediate transfer belt 11 is rotated in the return direction by the amount of rotation in the forward direction to align the transfer position of the second color.
By repeating such an operation of the transfer belt 11 four times, an image in which four colors are superimposed is formed on the intermediate transfer belt 11.

FIG. 2 shows a contact / separation mechanism of the intermediate transfer belt 11. The contacting / separating mechanism includes a supporting member 22 provided on the pulley 21 side facing the photosensitive drum 9, a supporting member 24 supporting the tension pulley 23 side, and a cam member 25. Each of the support members 22 and 24 has a support shaft 26 and 27 supported on the unit side (that is, the fixed side) of the transfer section.
It is possible to swing about. Support members 22, 2
A cam member 25 is arranged between the facing surfaces of the support member 4, and the support members 22 and 24 are pressed against the cam member 25 by an urging member (not shown). The cam member 25 is composed of an eccentric cam, and each support member 22,
The distance to the facing surface of 24, that is, the cam lift changes as the cam member 25 rotates. Therefore, when the cam member 25 is driven by a half rotation from the state shown in FIG. 2, the support member 22 swings to the right in the figure, and the intermediate transfer belt 11 is separated from the photosensitive drum 9. In this case, the support member 24 also moves rightward in the figure by the same amount, and the tension of the intermediate transfer belt 11 is maintained.

FIG. 3 is a perspective view showing a contact / separation mechanism of the intermediate transfer belt 11. As shown in the figure, the rotation shaft 28 of the cam member 25 is connected to the transfer belt contact / separation clutch 3 in half rotation steps.
1 is attached, and the half rotation step drive of the cam member 25 is performed by the rotation of the drive motor 32. That is, the cam member 25 is step-driven by half a rotation by the drive motor 32, and the intermediate transfer belt 11 is alternately brought into contact with and separated from the intermediate transfer belt 11 in accordance with the drive.

In the multicolor image forming apparatus of this embodiment, the switchback mechanism is not operated when forming an image of only one color. That is, the intermediate transfer belt 11 is rotated only in the forward direction while being in contact with the photosensitive drum 9. The paper transfer roller 13 remains in contact with the intermediate transfer belt 11, and the images transferred to the intermediate transfer belt 11 are continuously transferred onto the transfer paper.

FIG. 4 shows a drive mechanism for the intermediate transfer belt 11. The intermediate transfer belt drive motor 41 is a stepping motor, and rotates the drive roller 42 of the intermediate transfer belt 11. When forming an image of two or more colors, the intermediate transfer belt drive motor 41 is rotated forward and backward,
The intermediate transfer belt 11 is rotated in the forward direction and the return direction. Further, when forming an image of one color, only the forward rotation is performed, and the intermediate transfer belt 11 is forwardly rotated.

A flywheel 43 is mounted coaxially with the intermediate transfer belt drive roller 42 via an electromagnetic clutch 44. By turning the electromagnetic clutch 44 on and off, the flywheel 43 is connected to and disconnected from the intermediate transfer belt drive roller 42. By connecting the flywheel 43 to the intermediate transfer belt drive roller 42, the intermediate transfer belt 11 runs stably and stable image formation is performed. However, when images of two or more colors are formed, in the switchback system, the intermediate transfer belt 11 alternately repeats the rotations in the forward and return directions as described above, so that the inertial force of the flywheel 43 is smooth. It interferes with the operation. Therefore, when creating images of two or more colors, the flywheel 43
Are separated from the intermediate transfer belt drive roller 42.

FIG. 5 shows a drive mechanism for the paper transfer roller 13. The paper transfer roller 13 is rotationally driven by transmitting the rotational force of the drive motor 51 via the timing belt 52 and the gear train 53. Here, when forming images of two or more colors, the paper transfer roller 13 is not contacted with the intermediate transfer belt 11 during the primary transfer. Therefore, the operation of the paper transfer roller 13 does not adversely affect the speed of the intermediate transfer belt 11. However, in the case of one-color image formation, if the intermediate transfer belt 11 is operated without connecting the flywheel 43 to the intermediate transfer belt drive roller 42, the photosensitive drum 9
When the rotational fluctuation of the paper transfer roller 13 occurs during the primary transfer between the intermediate transfer belt 11 and the intermediate transfer belt 11, it affects the linear velocity of the intermediate transfer belt 11. As a result, a linear velocity difference may occur between the photoconductor drum 9 and the intermediate transfer belt 11, and a primary transfer defect may occur.

Therefore, when forming a one-color image, the electromagnetic clutch 4 is used.
4 is turned on and the intermediate transfer belt drive roller 42 and the flywheel 43 are connected to increase the inertial force of the intermediate transfer belt 11 and make it less susceptible to the rotational fluctuation of the paper transfer roller 13. As a result, the intermediate transfer belt 11 can be stably run and a good image can be obtained when forming a one-color image.

[0019]

As described above, the multicolor image forming apparatus of the present invention separates the flywheel from the side of the intermediate transfer belt to form an image of only one color when forming images of two or more colors. In the case of forming an image of only one color, by connecting to each other without forming an unnecessary load on the forward and reverse operations of the intermediate transfer belt when forming an image of two or more colors. In addition, even if the paper transfer roller has uneven rotation, the inertial force of the flyhole can minimize this effect, and stable image formation can be realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a multicolor image forming apparatus of the present invention.

FIG. 2 is a schematic side view showing a contact / separation mechanism of an intermediate transfer belt.

FIG. 3 is a perspective view showing a contacting / separating mechanism of an intermediate transfer belt.

FIG. 4 is a cross-sectional view showing a drive mechanism of an intermediate transfer belt.

FIG. 5 is a perspective view showing a drive mechanism of a paper transfer roller.

[Explanation of symbols]

 1 Color Image Reading Device 2 Illumination Lamp 3 Mirror Group 4 Lens 5 Color Sensor 6 Polygon Mirror 7 f / θ Lens 8 Reflection Mirror 9 Photoreceptor Drum 10 Developer 11 Intermediate Transfer Belt 12 Conveying Roller 13 Paper Transfer Roller 14 Paper Conveying Unit 15 Fixing device 21 Pulley 22 Supporting member 23 Tension pulley 24 Supporting member 25 Cam member 26, 27 Support shaft 28 Rotating shaft 31 Transfer belt contact / separation clutch 32 Drive motor 41 Intermediate transfer belt drive motor 42 Drive roller 43 Flywheel 44 Electromagnetic clutch 51 Drive Motor 52 Timing belt 53 Gear train

Claims (2)

[Claims] 1. A multicolor image is obtained by sequentially transferring visible images of different colors sequentially formed on a photoconductor onto an intermediate transfer belt so that the superimposed images are collectively transferred onto a transfer paper. In a multicolor image forming apparatus, a drive mechanism that drives the intermediate transfer belt in a transfer direction and a direction opposite to the transfer direction, a flywheel that rotates with the driving of the intermediate transfer belt, and the flywheel that performs the intermediate transfer. A clutch for connecting or disconnecting the belt and a belt contacting / separating mechanism for contacting / separating the intermediate transfer belt with respect to the photoconductor are provided, and the flywheel is used as the intermediate transfer belt when copying two or more colors. A multi-color image forming apparatus, characterized in that the flywheel is separated from the intermediate transfer belt when they are connected to each other and one-color copying is performed. 2. The intermediate transfer belt, when copying two or more colors, transfers a visible image of each color from the photoconductor to the intermediate transfer belt, and then separates from the photoconductor and feeds it back to the initial position. 2. The multicolor image forming apparatus according to claim 1, wherein the transfer of the next visible image is performed by superimposing it on the previous visible image by moving to the first visible image.